1. Field of the Invention
The present invention relates to a mobile communication terminal, and in particular to a speaker device adapted to be capable of providing high quality sound.
2. Description of the Related Art
Typically, a mobile communication terminal is provided with a space for mounting a speaker device, which is limited in size due to the limitation of the size of such a mobile communication terminal. Therefore, the improvement of sound quality and clearness can be expected depending on how to use the space.
Nowadays, in order to provide a speaker device suitable for DMB (Digital Multimedia Broadcasting), a separate speaker unit is additionally provided, beyond a speaker unit for outputting a receiving sound and bell sound. In order to allow a user to enjoy the DMB, what is needed is high quality audio performance for outputting a sound resembling the original sound.
In the past, attempts had been made for improving sound volume and quality by fixing a speaker and securing a resonant space for sealing. With this measure, an increase in sound pressure and partially in bass can be expected. However, it is still required to further improve sound quality, clearness, and THD (Total Harmonic Distortion). In order to solve this problem, a method for improving a bass region by implementing a speaker device employing a diaphragm structure has been developed.
FIG. 1 illustrates an example of a speaker device 100 of a mobile communication device, which employs a conventional diaphragm structure, wherein the speaker device 100 includes a speaker housing having a sub-housing 101a and a cover 101b. The speaker housing is provided with a mounting space 102a for mounting a speaker unit 109, and a resonant space 102b connected to the mounting space 102a. 
One side of the sub-housing 101a is opened, and a plurality of diaphragms 113 of various shapes is formed inside the sub-housing 101a. The diaphragms 113 serve to divide lie internal space of the sub-housing 101a. Such a speaker device employing the above-mentioned diaphragm structure should be improved in terms of THD which is a principal cause deteriorating high quality audio performance.
Like this, with the existing constructions of speaker devices, there are limitations in providing a sound resembling an original sound when enjoying DMB or the like. In addition, because users typically enjoy DMB in a state in which the volume is increased, speaker devices should be improved in terms of sound characteristics, even in the state in which the volume is increased. Furthermore, it is required to develop a speaker device capable of improving clearness and THD while complementing areas vulnerable in bass reproducing characteristics.